This disclosure relates generally to radio transmissions, and more specifically to RF tuner accessories that communicate with a media player such as a portable media device (“PMD”).
There are a number of technologies whereby AM and FM radio stations are able to transmit digital information along with their analog signals. This is typically done by modulating low-energy sidebands within the normal station bandwidth using known digital modulation schemes.
An early technology deployed in Europe is known as Radio Data System (“RDS”); a U.S. counterpart, officially known as Radio Broadcast Data System (“RBDS”), is very often also referred to as RDS. In an RDS broadcast, a small amount of digital data relevant to the broadcast is included with the analog broadcast. The information (i.e., metadata) is structured (differently in Europe and the U.S.) to include such information as time, track/artist information, station identification, and program type (e.g., news, sports, weather, talk, top 40, country, jazz, classical, and rhythm and blues). It will be appreciated that the RDS system, while not improving the audio quality or providing additional program content, provides useful information to the listener.
Another set of technologies provide digital audio, in addition to the metadata about the content being played. High-quality audio can be transmitted using less bandwidth than conventional AM or FM radio by digitally encoding the audio stream at the source, and then decoding it at the destination. There are a number of formats for digital audio, but a particular in-band on-channel (“IBOC”) technology developed by iBiquity Digital Corporation (“iBiquity”) has been selected as a standard by the U.S. Federal Communications Commission (FCC). The latest version of the standard is officially referred to as In-Band/On-Channel Digital Radio Broadcasting Standard NRSC-5A promulgated by the National Radio Systems Committee.
As stated in Wikipedia, “HD Radio technology . . . enables AM and FM radio stations to simulcast both digital and analog audio within the same channel (a hybridized digital-analog signal) as well as add new FM channels and text information.” HD Radio, at least in stylized forms, is a registered trademark of iBiquity. It is also viewed by some as an acronym for “Hybrid Digital” radio technology. Thus, iBiquity's technology is a species of IBOC technology for transmitting digital radio and analog radio broadcast signals simultaneously within the frequency band allocated to the analog radio station.